The present invention relates to magnetic recording systems, and more particularly to high track density recording systems employing buried servos for faithful track following operations.
Buried servos have been recognized as an effective means for faithful track positioning control. A prior art system typically shown and described in U.S. Pat. Nos. 4,313,140, 4,314,289 and 4,318,141 employs a single-gap transducer for recording a data signal while at the same time sensing prerecorded servo control signals. To effect this simultaneous writing and reading operation, it is necessary to minimize the effect of the counterelectromotive force (abbreviated counter emf) induced by the recording data signal on the signal-to-noise ratio of the servo control signals. For this purpose, the recording circuit of the system includes an AC bias and a high-pass filter to improve the signal-to-noise ratio of the servo control signals. A notch filter is further required to suppress the data signal of the frequencies to reduce the counter emf.
However, the signal-to-noise ratio of the servo control signals has been found to be still not satisfactory and the use of the aforesaid AC bias and filters adds to complexity with an attendant cost increase.